JP6445137B2 - X-ray microscope - Google Patents

Description

  The present invention relates to an imaging-type electromagnetic microscope, for example, an imaging-type X-ray microscope using magnetic circular dichroism for obtaining a magnetic structure.

  X-ray microscopes have been developed with higher resolution by using high-intensity X-rays of synchrotron radiation. The X-ray microscope technology uses (1) a scanning condensing X-ray microscope that scans the sample using condensing X-rays, and (2) an X-ray lens such as a Fresnel zone plate (FZP). And an imaging X-ray microscope that forms a sample image on a camera. In the scanning condensing X-ray microscope, since a high-intensity X-ray is irradiated to a minute region of the sample, there is a problem of causing irradiation damage to the sample. Further, when measuring the microscope while changing the external environment of the sample, the sample scanning time is long, and there are problems such as sample drift and intensity drift during scanning measurement.

  One imaging type X-ray microscope irradiates the entire surface of the sample with X-rays and forms an image of the sample on the camera, so that the exposure time tends to be long. However, in terms of sample damage, this microscope has a longer length of weak X-rays compared to the case where measurement is performed using focused X-rays even when the X-ray dose in the entire measurement is the same as that of the focused X-ray microscope. Since irradiation is performed for a long time, it is excellent in reducing irradiation damage to the sample. On the other hand, if the exposure time is long, image blur due to sample drift becomes a problem. For this problem, use the method used in electron microscopes (total exposure time length is divided into multiple images to acquire multiple images, and then correct and integrate the sample position deviation (sample drift) between the acquired images. This can be improved by using a drift correction method. However, the resolution of the imaging X-ray microscope is not determined only by the X-ray optical conditions, such as being determined by the outermost ring width of the FZP. However, except for this resolution problem, the imaging X-ray microscope is an excellent X-ray microscope technology.

  Further, the X-ray microscope technology includes a technology that uses the magnetic circular dichroism of synchrotron radiation X-rays. Since this technique is a direct measurement of magnetism by X-rays, that is, “Photon-in Photon-out measurement”, measurement in a large external magnetic field environment or the like is possible. Moreover, since this technology has element selectivity, it has attracted attention as a new magnetic measurement technology that can measure magnetic hysteresis that enables element identification, magnetization change in a minute portion, and the like.

  However, the absorption change due to magnetic circular dichroism is only a few percent of the X-ray absorption at most. For this reason, the magnetic measurement technique using X-ray magnetic circular dichroism requires long-time measurement using high-intensity X-rays. Conventionally, a scanning condensing X-ray microscope has been used as a microscopy method using magnetic circular dichroism. In particular, element identification magnetic hysteresis (ESMH) measurement in a minute region can obtain magnetic changes at crystal grains and grain boundaries and magnetic information of elements. Therefore, ESMH measurement is useful for measurement at high resolution (submicron to nanometer order). On the other hand, the scanning condensing X-ray microscope has weak magnetic circular dichroism signal intensity, so (1) displacement of the sample position due to long measurement time, and (2) long time sample under strong magnetic field Concentrated X-rays are sample drifts consisting of thermal drift due to holding, (3) displacement due to force received from an external magnetic field, and (4) sample vibration caused by vibration transmitted from the cooling system of the external magnetic field application device. This is a big problem in high-resolution measurement using the.

  On the other hand, magnetic measurement by an imaging X-ray microscope has the following problems. In magnetic circular dichroism, the difference between the amount of X-ray absorption by clockwise circularly polarized X-rays and the amount of X-ray absorption by counterclockwise circularly polarized X-rays is magnetic absorption. However, in an X-ray optical system that generates circularly polarized light, it is difficult to make the intensity of right-handed circularly polarized X-rays equal to the intensity of counterclockwise circularly polarized X-rays. It is necessary to accurately measure the intensity of X-rays.

  In the case of an X-ray microscope using focused X-rays, this problem can be solved by placing transmission intensity measurement detectors such as an ion chamber before and after the sample and simultaneously measuring the intensity. However, in the case of an imaging X-ray microscope, it is difficult to simultaneously measure the intensity distribution by placing cameras before and after the sample. Even if a half mirror is placed in front of the sample and a part of the incident intensity is measured by another camera, the alignment accuracy to the light receiving element of the camera, the spread of X-rays at the position of the X-ray / light conversion element, The reflectance accuracy of the mirror is a problem and is not realistic.

  Further, in the imaging X-ray microscope, when the intensity of the irradiated X-ray is not uniform at the spatial resolution level, it is necessary to correct the spatial nonuniformity of the incident X-ray intensity. This problem is not a problem with an X-ray microscope using condensed X-rays, and is a problem specific to an imaging X-ray microscope. As a method for solving this problem, a method of measuring the incident X-ray intensity distribution for each of the clockwise circularly polarized X-ray and the counterclockwise circularly polarized X-ray before the measurement can be considered. Even in this case, it is necessary to separately measure the incident X-ray intensity distribution. In addition, the temporal stability of the incident optical system becomes a problem. For this reason, it is not sufficient to obtain a magnetic absorption image having a signal of several percent or less of the absorptance, and the problem inherent to the imaging X-ray microscope cannot be solved.

  As one of the inventions for solving the above problems, (1) when the sample is repeatedly moved between a plurality of regions dividing the maximum field of view, the region including the sample image and the sample each time the sample is moved An image acquisition unit that acquires a field image corresponding to the maximum field of view including both of the regions not including the image of (2), and (2) within the maximum field of view of the region not including the sample image and the region including the sample image An electromagnetic microscope having a computing device that calculates a sample absorption image using a plurality of the field images having different positional relationships is proposed.

  As another invention for solving the above problems, (1) a polarization switching mechanism of circularly polarized X-rays, and (2) when a sample is repeatedly moved between a plurality of regions dividing the maximum field of view, An image acquisition unit that acquires a field image corresponding to the maximum field of view including both an area including the image of the sample and an area not including the image of the sample each time the sample is moved; and (3) movement of the sample A control unit that switches the polarization of the circularly polarized X-rays by controlling the polarization switching mechanism in synchronization with (4) within the maximum field of view of the region not including the sample image and the region including the sample image An arithmetic unit that executes a process of calculating a sample absorption image using a plurality of the field images having different positional relationships and a process of calculating a magnetic absorption image using the plurality of sample absorption images having different polarizations at the time of acquisition; An X-ray microscope having

  According to a representative example of the present invention, a high-resolution sample in which the influence of sample drift, irradiation optical system drift, time variation of incident X-ray intensity, etc. is corrected while reducing the time of irradiation electromagnetic wave or X-ray intensity distribution measurement. An absorption image or a magnetic absorption image can be acquired. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

The figure explaining the acquisition operation | movement of the microscope visual field image by the X-ray microscope which concerns on an Example. The figure explaining other acquisition operation | movement of the microscope visual field image by the X-ray microscope which concerns on an Example. The figure explaining the calculation principle of the sample absorption image by the X-ray microscope which concerns on an Example. The figure which shows the image of the magnetic structure and X-ray microscope image (magnetic absorption image) which were acquired with the method which concerns on an Example. The figure explaining the other acquisition principle of the sample absorption image by the X-ray microscope which concerns on an Example. The figure which shows the schematic structural example of an X-ray microscope.

Mode for carrying out the invention

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the Example of this invention is not limited to the example mentioned later, A various deformation | transformation is possible in the range of the technical idea.

(1) Basic concept In the imaging-type electromagnetic microscope (or X-ray microscope), the measurement of the intensity distribution of irradiated X-rays in the absence of the sample and the sample to be executed subsequently are performed before the measurement of the sample. By repeating the measurement of the sample absorption image in a state where there is, the time change of the irradiation X-ray optical system can be suppressed below the resolution. In addition, the sample drift can be corrected by combining with the drift correction described above.

  However, in this method, it is necessary to repeat the measurement in the presence of the sample and the measurement in the absence of the sample (measurement of the intensity distribution of the X-ray as a background), so a pair of measurements (in the presence of the sample) The time required for the measurement and the measurement without the sample) is twice the time required for each measurement. Magnetic measurement has a low signal intensity, so it is practically difficult if the measurement time is doubled even though it is a long time measurement.

  Therefore, the sample is moved so that the sample position does not overlap before and after the movement in the measurement field having a size of twice or more of the sample size, and a field image corresponding to the maximum field of view is obtained before and after the movement (each sample position). A method of performing the intensity distribution measurement of the incident X-ray and the sample measurement at a time by taking an image is adopted. Furthermore, by applying image calculation and sample drift correction to the visual field image (including both the background region and the sample image region) acquired by this method, the measurement time is not doubled as before, It is possible to acquire a high-resolution sample absorption image and further a magnetic absorption image.

(2) Example 1
(2-1) Basic Configuration FIG. 6 shows a schematic configuration of an imaging type X-ray microscope used in this embodiment. In this embodiment, for example, an undulator (not shown) installed in a SPring-8 radiation ring (not shown) is used as the X-ray source. X-rays generated from the X-ray source are monochromatized into neodymium L ₂ absorption edge energy X-rays by a liquid nitrogen cooled two-crystal spectrometer 21. Note that the monochromization of X-rays depends on the measurement target. The monochromatic X-ray is condensed at the pinhole position after the high-order light (tertiary light) is removed by the front mirror 23 arranged downstream of the two-crystal spectrometer 21, and the incident X-ray is vertically and horizontally A divergence angle and a beam shape are formed. X-ray neodymium L ₂ absorption edge energy, X-rays absorption and magnetic absorption of neodymium element in the neodymium magnet (Nd-Fe-B magnet) is finely adjusted so as to measure.

  An upstream slit 24 is inserted on the upstream side of the sample 1 so as to hide the upper half of the Fresnel zone plate (FZP) 26 used as an X-ray lens. Sample 1 is placed on a sample stage (not shown). The sample stage can switch the sample position in a plane perpendicular to the X-ray axial direction by a known moving mechanism (not shown). A downstream slit 25 is disposed at a position where X-rays irradiated to the FZP 26 after the sample 1 passes are condensed. The mounting position of the downstream slit 25 is adjusted so as to hide the lower half of the X-rays that have passed through the FZP 26.

  X-rays that have passed through the downstream slit 25 are imaged on the imaging surface of the X-ray camera 27. A visual field image corresponding to the maximum visual field is output from the X-ray camera 27 to the arithmetic unit 28. The calculation device 28 is a so-called calculator, and performs image processing on the field image based on a predetermined calculation procedure to calculate a magnetic absorption image of the sample 1. The arithmetic device 28 includes a memory used for image storage and arithmetic processing. Here, the polarization direction of the X-ray is switched by the diamond phaser 22 disposed between the two-crystal spectrometer 21 and the front mirror 23. The switching of the polarization direction is controlled in synchronization with the movement of the sample 1 within the visual field. This control is performed by the control unit 29. In the present embodiment, the diameter of the FZP 26 is about 100 μm, and the microscope field (maximum field of view) in the X-ray camera 27 is a semicircle having a diameter of 100 μm.

(2-2) Acquisition of microscope field image Hereinafter, with reference to FIG. 1, an operation for acquiring a microscope field image by the imaging X-ray microscope of the present embodiment will be described. As shown in the upper part of FIG. 1, a semicircular microscope visual field 2 having a diameter of 100 μm includes a sample 1 of a neodymium magnet having a size of 25 × 30 μm. The size of sample 1 must have a diagonal line of 50 μm or less because sample 1 must be completely within the area where microscope field 2 is divided in half, and the maximum field area (semicircular microscope field 2 ) 30% or less. In other words, the size of the sample 1 is 60% or less of the area of the region obtained by dividing the microscope visual field 2 in half.

  In the lower part of FIG. 1, photographs obtained in actual experiments are arranged. The uppermost photograph shows a background image 3 obtained by cutting out a region of interest (ROI) set on the X-ray camera 27 from an image corresponding to a semicircular microscope field of view 2 having a diameter of 100 μm.

  In the imaging X-ray microscope according to the present embodiment, a pair of visual field images in which the position of the sample 1 is different (before and after movement) are acquired for each of the two left and right circularly polarized lights. Here, the left and right circularly polarized light can be switched using a diamond phaser 22 installed upstream of the optical system. When switching between left and right circularly polarized light, the angle between the diamond phase shifter 22 and the X-rays changes, so that the intensity of the entire field of view varies by about 5%. In the present embodiment, this switching is possible at a maximum speed of 20 Hz. For this reason, in this embodiment, the polarization switching is performed faster than the movement of the sample 1.

  Hereinafter, clockwise circularly polarized light is expressed as + (plus), and counterclockwise circularly polarized light is expressed as-(minus). Further, the left half area in the microscope field 2 is denoted as field A, and the right half area is denoted as field B.

  First, the sample 1 is placed in the field of view A, and an image of the microscope field of view 2 is obtained with clockwise circular polarization. Thereby, the visual field A + in which the sample 1 is included and the background B + in which the sample 1 is not included can be obtained simultaneously. The photograph on the left side of the second row corresponds to a field image including the sample 4 arranged in the field A with clockwise circular polarization.

  Next, the image of the microscope visual field 2 is obtained by switching the polarization only counterclockwise while keeping the position of the sample 1 as it is. As a result, it is possible to simultaneously obtain the visual field A- in which the sample 1 is included and the background B- in which the sample 1 is not included. The photograph on the right side of the second row corresponds to a field image including the sample 5 arranged in the field A with counterclockwise circularly polarized light.

  Subsequently, the sample position is moved to the visual field B, and the polarized light is switched to the clockwise circularly polarized light to obtain an image of the microscope visual field 2. As a result, the visual field B + including the sample 1 and the background A + not including the sample 1 can be obtained simultaneously. The photograph on the left side of the third row corresponds to a field image including the sample 6 arranged in the field B with clockwise circular polarization.

  Further, the image of the microscope field of view 2 is obtained by switching the polarization only counterclockwise while keeping the position of the sample 1 as it is. Thereby, the visual field B- in which the sample 1 is included and the background A- in which the sample 1 is not included can be obtained simultaneously. The photograph on the right side of the third row corresponds to the field image including the sample 7 arranged in the field B with counterclockwise circularly polarized light.

  Thereafter, the imaging X-ray microscope repeats the above-described processing from the beginning. That is, the sample 1 is moved to the visual field A, and the polarized light is switched to the clockwise circularly polarized light to acquire the image of the microscope visual field 2. This operation is repeated until an image having a sufficient S / N is obtained. Each photograph shown in the lower part of FIG. 1 is an image obtained by exposure for 195 seconds. In the example, the image acquisition at 195 seconds exposure was looped 22 times, and a total of 88 (= 22 × 4) images were obtained.

  However, when an apple-type undulator (not shown) is used to generate circularly polarized light, it takes time to switch the polarized light. In addition, an undulator using a permanent magnet cannot obtain the same intensity with left and right circularly polarized light. When the movement of the sample 1 can be performed at a higher speed than the polarization switching, a slight increase in speed can be achieved by rearranging the measurement order as shown in FIG.

  In the case of FIG. 2, first, the sample 1 is placed in the field of view A, and an image of the microscope field of view 2 is obtained with clockwise circular polarization. Next, the position of the sample 1 is moved to the field of view B, and an image of the microscope field of view 2 is obtained with the clockwise polarization. Thereafter, the position of the sample 1 is moved again to the visual field A, and the polarized light is switched to the counterclockwise polarized light to obtain an image of the microscope visual field 2. Further, the sample 1 is moved to the field of view B, and an image of the microscope field of view 2 is obtained with the left-hand polarized light. When this loop is repeated, the polarization is switched twice in one loop. The number of times of switching is half that in the case of FIG. 1 (four times). In addition, in the case of the acquisition operation of FIG. 1 and the case of the acquisition operation of FIG. 2, there is no difference in the obtained images, and the same effect is obtained.

(2-3) Sample Absorption Image Calculation Processing A method for calculating the sample absorption image of the sample 1 from four field images for one loop will be described with reference to FIG.

  First, the arithmetic unit 28 divides the visual field image including the sample 4 arranged in the visual field A with the clockwise circular polarization by the visual field image including the sample 6 arranged in the visual field B with the clockwise circular polarization. A sample absorption image corresponding to each of A and visual field B is calculated. By this division operation, I1 / I0 is calculated in the field of view A. I1 is the intensity distribution of the measurement region including the sample 1, and I0 is the intensity distribution of the background region. Thereby, the arithmetic unit 28 obtains the sample absorption image 8 when observing the sample 4 arranged in the field A using the clockwise circularly polarized light normalized by the incident intensity of the field A.

  On the other hand, in the field of view B, I0 / I1 is calculated by this division operation. In this calculation formula, the intensity distribution in the measurement region is a denominator, while the intensity distribution in the background region is a numerator. Therefore, for the visual field B, the arithmetic unit 28 further obtains the reciprocal of the result calculated by I0 / I1. Thereby, the arithmetic unit 28 obtains the sample absorption image 9 obtained by observing the sample 6 arranged in the field B using the clockwise circularly polarized light normalized by the incident intensity of the field B.

  The same applies to counterclockwise circularly polarized images. The arithmetic unit 28 divides the image of the microscope field 3 including the sample 5 arranged in the field A with counterclockwise circular polarization by the image of the microscope field 3 including the sample 7 arranged in the field B with counterclockwise circular polarization. Thus, an absorption image corresponding to each of the visual field A and the visual field B is calculated. By this division operation, I1 / I0 is calculated in the field of view A. As a result, a sample absorption image 10 in the case of observing the sample 5 arranged in the field A using the left-handed circularly polarized light normalized by the incident intensity of the field A is obtained.

  On the other hand, in the field of view B, I0 / I1 is calculated by this calculation. In this calculation formula, the intensity distribution in the measurement region is a denominator, while the intensity distribution in the background region is a numerator. Therefore, for the visual field B, the arithmetic unit 28 further calculates the reciprocal of the result calculated by I0 / I1. Thereby, the arithmetic unit 28 obtains the sample absorption image 11 when observing the sample 7 arranged in the field B using the left-handed circularly polarized light normalized by the incident intensity of the field B.

  By this calculation, a sample absorption image in which the intensity distribution of incident X-rays, the intensity fluctuation due to polarization switching, and the intensity change due to time change are corrected is obtained, and drift correction relating to the sample position is possible. In this example, the sample absorption image 8 of the sample arranged in the field A with right-handed circularly polarized light, the sample absorption image 9 of the sample arranged in the field of view B with right-handed circularly polarized light, and placed in the field of view A with left-handed circularly polarized light The sample absorption image 10 of the sample and the sample absorption image 11 of the sample arranged in the field of view B with left-handed circularly polarized light are obtained for each 22 sheets. The arithmetic unit 28 corrects these drifts and aligns the sample position.

  For drift correction, for example, a drift correction program for an electron microscope is used. The arithmetic unit 28 integrates the drift-corrected images for each field of view, thereby integrating the sample absorption image 12 of the sample placed in the field of view A with clockwise circular polarization and the field of view B with the clockwise circular polarization. An integrated sample absorption image 13 of the sample, an integrated sample absorption image 14 of the sample arranged in the field A with counterclockwise circular polarization, and an integrated sample absorption image 15 of the sample arranged in the field B with counterclockwise circular polarization are obtained. These accumulated sample absorption images 12, 13, 14, and 15 correspond to images of 4290 (= 195 seconds × 22 sheets) exposure, respectively.

  Further, the arithmetic unit 28 in the present embodiment includes the integrated sample absorption image 12 of the sample arranged in the field of view A with clockwise circular polarization and the integrated sample absorption image 13 of the sample arranged in the field of view B with clockwise circular polarization. Align and add to obtain a clockwise circular polarization integrated sample absorption image. Similarly, the arithmetic unit 28 adds the integrated sample absorption image 14 of the sample arranged in the field A with counterclockwise circular polarization and the integrated sample absorption image 15 of the sample arranged in the field B with counterclockwise circular polarization. A counterclockwise circularly polarized light integrated sample absorption image is obtained. By this calculation, an image corresponding to exposure of 8580 seconds is obtained for the sample portion. At this time, the portion where the two images did not overlap was trimmed.

  FIG. 4A shows a result (X-ray absorption microscope image 16 of the sample) obtained by aligning and adding the clockwise circularly polarized sample absorption image and the counterclockwise circularly polarized sample absorption image. As shown in the figure, the background intensity distribution disappears, and the contrast on the sample can be clearly confirmed. In addition, the refraction contrast 17 occurring in the thin region of the sample can also be confirmed. Since drift correction is working correctly, there is no blurring due to integration. A μt image (μ: linear absorption coefficient, t: film thickness) can be obtained by calculating the logarithm of the X-ray absorption microscope image 16 shown in FIG.

(2-4) Magnetic Absorption Image Calculation Processing The magnetic absorption image is expressed as {μ, where μ (+) is the linear absorption coefficient for clockwise circularly polarized light and μ (−) is the linear absorption coefficient for counterclockwise circularly polarized light. It can be obtained by the calculation of (+) t−μ (−) t} / {μ (+) t + μ (−) t}. For example, the image of μ (+) t is the addition of the accumulated sample absorption image 12 of the sample arranged in the field A with clockwise circular polarization and the accumulated sample absorption image 13 of the sample arranged in the field B with clockwise rotation polarized light. It is a logarithmic image of the clockwise circular polarization sample absorption image which is a result. Similarly, the image of μ (−) t is an integrated sample absorption image 14 of a sample arranged in the field A with counterclockwise circular polarization and an integrated sample absorption image 15 of the sample arranged in the field B with counterclockwise circular polarization. It is a logarithmic image of the counterclockwise circularly polarized sample absorption image which is the addition result of. The image of {μ (+) t + μ (−) t} is a logarithmic image of the X-ray absorption microscope image 16 shown in FIG.

  The arithmetic unit 28 uses these three images to calculate {μ (+) t−μ (−) t} / {μ (+) t + μ (−) t}, as shown in FIG. An X-ray magnetic absorption image 18 of the sample shown is calculated. In FIG. 4B, the magnetized region is indicated by oblique lines for patent drawing. In FIG. 4B, the refractive contrast 17 is erased due to the difference between the left and right circularly polarized light. In addition, among the magnetizations perpendicular to the paper surface, there is a distinction between the (+) magnetization region 19 in which the magnetization vector is in the normal direction and the (−) magnetization region 20 in which the magnetization vector is in the direction penetrating the paper surface. it can. Further, a region having a high concentration in the X-ray magnetic absorption image 18 is a region having a high Nd concentration and is a neodymium oxide precipitate. This region is paramagnetic and has almost no magnetization. Conversely, the region with a low Nd concentration is an Nd—Fe—B crystal region, and the magnetization is measured.

(2-5) Summary As described above, when the imaging X-ray microscope according to the present embodiment is used, the X-ray absorption microscope image 16 and the X-ray magnetic absorption image 18 which is the magnetic structure of the sample are compared with the conventional one. Can be measured in a short time.

(3) Example 2
The calculation method of the X-ray absorption microscope image 16 is not limited to the method of the first embodiment. For example, if the accumulated sample absorption image 12 of the sample arranged in the field of view A with clockwise circular polarization and the accumulated sample absorption image 14 of the sample arranged in the field of view A with counterclockwise circular polarization are aligned and added, An X-ray absorption microscopic image 16 of the sample in A can be obtained. Similarly, if the accumulated sample absorption image 13 of the sample arranged in the field of view B with clockwise circular polarization and the accumulated sample absorption image 15 of the sample arranged in the field of view B with counterclockwise circular polarization are aligned and added, An X-ray absorption microscope image 16 of the sample in the field B can be obtained. The X-ray absorption microscope images 16 here are all images equivalent to exposure to 8580 seconds.

  Also, the difference between the logarithmic image of the accumulated sample absorption image 12 of the sample placed in the field of view A with clockwise circular polarization and the logarithmic image of the accumulated sample absorption image 14 of the sample placed in the field of view A with counterclockwise circular polarization is By calculating, an X-ray magnetic absorption image 18 given by {μ (+) t−μ (−) t} / {μ (+) t + μ (−) t} can be obtained for the visual field A. . By performing the same calculation in the field of view B, the X-ray magnetic absorption given by {μ (+) t−μ (−) t} / {μ (+) t + μ (−) t} for the field of view B An image 18 can be obtained.

(4) Example 3
Here, an imaging X-ray microscope that can further shorten the measurement time compared to the above-described embodiment will be described. Specifically, if the shape of the front mirror 23 in the X-ray microscope shown in FIG. 6 is optimized, it can be used as a condenser lens for removing high-order light (third-order light) and condensing X-rays near the sample. It becomes possible to irradiate the sample 1 with an X-ray intensity about 20 times that of the first embodiment. The diffraction efficiency can be increased by 1.8 times with FZP26, which is optimized for the neodymium L2 absorption edge energy. By optimizing these optical systems, the exposure time required to obtain the X-ray magnetic absorption image 18 could be reduced to about 300 seconds. However, due to the limit of the dynamic range of the X-ray camera 27, the total of 13 exposures for 23 seconds was added.

(5) Example 4
In the first embodiment, the microscope visual field 2 (FIG. 1) is divided into two, but the microscope visual field may be divided into three or more. FIG. 5 shows an example in which a circular microscope field of view is divided into four. In the case of FIG. 5, the size of the sample 1 needs to be smaller than 16% of the circular overall field of view 30. Here, each region obtained by dividing the entire visual field 30 into four is referred to as a first visual field 31, a second visual field 32, a third visual field 34, and a fourth visual field 33. In this case, the sample 1 is moved to the first visual field 31, the second visual field 32, the third visual field 34, and the fourth visual field 33 in order, for example, in the clockwise direction. Get. At this time, if the sample 1 is present in the first field of view 31 and the second field of view 32, the circularly polarized light is clockwise. 3 is possible, the sample absorption image of sample 1 arranged in the first field of view 31 with clockwise circular polarization, the sample absorption image of sample 1 arranged in the second field of view 32 with clockwise circular polarization, A sample absorption image of sample 1 arranged in the third field of view 34 with counterclockwise circular polarization and a sample absorption image of sample 1 arranged in the fourth field of view 33 with counterclockwise circular polarization can be obtained.

  The contents of the subsequent arithmetic processing are the same as those in the first embodiment. In this embodiment, the sample absorption image of the sample 1 arranged in the first visual field 31 with the clockwise circular polarization, the sample absorption image of the sample 1 arranged in the second visual field 32 with the clockwise circular polarization, and the counterclockwise circular polarization 22 sample absorption images of the sample 1 arranged in the third visual field 34 and 22 sample absorption images of the sample 1 arranged in the fourth visual field 33 with left-handed circularly polarized light are obtained. These images are drift-corrected to align the sample position. For drift correction, for example, a drift correction program for an electron microscope is used. Accumulated sample absorption images obtained by measuring samples placed in the first field of view 31 with right-handed circularly polarized light, and samples placed in the second field of view 32 with right-handed circularly polarized light, by integrating the drift-corrected images. The integrated sample absorption image, the integrated sample absorption image obtained by measuring the sample placed in the third field of view 34 with counterclockwise circular polarization, and the integrated sample absorption image obtained by measuring the sample placed in the fourth field of view 33 with counterclockwise circular polarization Can be obtained.

  Next, an integrated sample absorption image obtained by measuring the sample 1 arranged in the first visual field 31 with clockwise circular polarization and an integrated sample absorption image obtained by measuring the sample 1 arranged in the second visual field 32 by clockwise circular polarization. If alignment is performed and addition is performed, a clockwise clockwise polarized sample absorption image can be obtained. Similarly, the position of the integrated sample absorption image obtained by measuring the sample 1 arranged in the third field of view 34 with the counterclockwise circularly polarized light and the integrated sample absorption image obtained by measuring the sample arranged in the fourth field of view 33 with the counterclockwise circularly polarized light. If they are combined and added, a counterclockwise circularly polarized sample absorption image can be obtained.

  Further, if the right-handed circularly polarized sample absorption image and the left-handed circularly polarized sample absorption image are aligned and added, an X-ray absorption microscope image 16 of the sample 1 similar to that shown in FIG. Further, by calculating the logarithm of the X-ray absorption microscope image 16, a μt image (μ: linear absorption coefficient, t: film thickness) can be obtained. The image of μ (+) t is an accumulated sample absorption image obtained by measuring the sample 1 arranged in the first visual field 31 with clockwise circular polarization and the sample 1 arranged in the second visual field 32 with clockwise circular polarization. It is a logarithmic image of a clockwise polarized sample absorption image obtained by adding up integrated sample absorption images. Similarly, the image of μ (−) t is an accumulated sample absorption image obtained by measuring the sample 1 arranged in the third visual field 34 with the counterclockwise circular polarization and the sample 1 arranged in the fourth visual field 33 with the counterclockwise circular polarization. Is a logarithmic image of the counterclockwise circularly polarized sample absorption image obtained by adding up the integrated sample absorption images obtained by measuring. An X-ray magnetic microscope image 18 of the same sample as in FIG. 4B is obtained by image calculation of {μ (+) t −μ (−) t} / {μ (+) t + μ (−) t}. It is done.

(6) Others The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and it is not necessary to provide all the configurations described. In addition, a part of one embodiment can be replaced with the configuration of another embodiment. Moreover, the structure of another Example can also be added to the structure of a certain Example. In addition, with respect to a part of the configuration of each embodiment, a part of the configuration of another embodiment can be added, deleted, or replaced.

1: Sample
2: Microscopic field with intensity distribution
3: Background image with intensity distribution cut out from microscope field of view 2
4: Sample placed in field of view A with clockwise circular polarization
5: Sample placed in field of view A with counterclockwise circularly polarized light
6: Sample placed in field of view B with clockwise circular polarization
7: Sample placed in field of view B with counterclockwise circularly polarized light
8: Sample absorption image of sample placed in field of view A with clockwise circular polarization
9: Sample absorption image of sample placed in field of view B with clockwise circular polarization
10: Sample absorption image of sample placed in field of view A with counterclockwise circularly polarized light
11: Sample absorption image of sample placed in field of view B with counterclockwise circularly polarized light
12: Accumulated sample absorption image of sample placed in field of view A with clockwise circular polarization
13: Accumulated sample absorption image of sample placed in field of view B with clockwise circular polarization
14: Integrated sample absorption image of sample placed in field of view A with counterclockwise circularly polarized light
15: Integrated sample absorption image of sample placed in field of view B with counterclockwise circularly polarized light
16: X-ray absorption microscope image of the sample
17: Refraction contrast
18: X-ray magnetic microscope image of the sample
19: + magnetization region
20:-Magnetization region
21: Two-crystal spectrometer
22: Diamond phaser
23: Front mirror
23A: Pinhole
24: Upstream slit
25: Downstream slit
26: Fresnel zone plate
27: X-ray camera
28: Arithmetic unit
29: Control unit
30: Overall view
31: First field of view
32: Second field of view
33: Fourth field of view
34: Third field of view

Claims (4)

A polarization switching mechanism for circularly polarized X-rays;
When the sample is repeatedly moved between a plurality of regions dividing the maximum field of view, the maximum field of view including both the region including the sample image and the region not including the sample image is moved each time the sample is moved. An image acquisition unit for acquiring a corresponding visual field image;
A controller that controls the polarization switching mechanism in synchronization with the movement of the sample to switch the polarization of the circularly polarized X-ray;
A process of calculating a sample absorption image using a plurality of field images having different positional relationships between a region not including the sample image and a region including the sample image, and a plurality of the sample absorption images having different polarizations at the time of acquisition An X-ray microscope comprising: an arithmetic unit that executes a process of calculating a magnetic absorption image using a computer. The X-ray microscope according to claim 1,
The maximum value of the area when projected onto a plane has a size of 30% or less of the maximum visual field in the image acquisition unit,
A moving mechanism that reciprocally moves the sample between a first region and a second region that bisect the maximum field of view;
The control unit synchronizes the reciprocation and switching of polarization of the circularly polarized X-ray. The X-ray microscope according to claim 1,
The maximum value of the area when projected onto a plane has a size of 15% or less of the maximum field of view in the image acquisition unit,
A moving mechanism that repeatedly moves the sample in order between the first to fourth regions that divide the maximum field of view into four equal parts;
The control unit switches between the polarization of the circularly polarized X-rays applied to the first and second regions and the polarization of the circularly polarized X-rays applied to the third and fourth regions, and the sample An X-ray microscope characterized by synchronizing the movement of the X-ray. The X-ray microscope according to claim 1,
The arithmetic unit is
The field-of-view image including the image of the sample in a first region that is one of the plurality of regions that divides the maximum field of view, and a second region that is the other one of the plurality of regions And correcting the sample positions of a plurality of images obtained by dividing by the visual field image including the sample image, and then integrating the corrected images to add the image of the sample to the first region. A process of calculating a first integrated image including:
After correcting the field image including the sample image in the second region by dividing the field image including the sample image in the first region by matching the sample positions of the plurality of images. A process of calculating a second integrated image including the image of the sample in the second region by integrating the corrected image;
A process of calculating the sample absorption image by performing integration after aligning the sample position of the first integrated image and the sample position of the second integrated image; and
A process for calculating the first integrated image, a process for calculating the second integrated image, and a sample absorption image are calculated for the field image acquired using the circularly polarized X-rays having different polarizations. A process to execute the process;
A process of calculating a logarithmic image for each of the sample absorption images;
A difference image between logarithmic images of the sample absorption image calculated for the circularly polarized X-rays having different polarizations is standardized by an addition image of logarithmic images of the sample absorption image calculated for the circularly polarized X-rays having different polarizations. And a process of calculating the magnetic absorption image.

Images